Millions of Americans take fish oil supplements, with the goal of benefiting from the much-hyped omega-3 fatty acids they contain. Even the American Heart Association — for now – recommends these supplements for people with a history of heart disease.

However, a large review of randomized trials has determined that fish oil supplements containing omega-3 fatty acids are ineffective for the prevention of heart disease. The analysis, published in JAMA Cardiology, pooled data from 10 randomized trials focusing on people who had had cardiovascular disease or were at high risk for heart disease.

Researchers concluded that they could find no association between regular consumption of the supplements and a lowered risk for death from heart disease, or nonfatal heart attacks or other major cardiovascular events. Moreover, the supplements did not benefit people with prior coronary heart disease, those with diabetes, people with high lipid levels, or in people using statins to combat high cholesterol. These findings applied to both the men and the women who took part in the trails reviewed.

Dr. Fialkow said the new findings suggest that because these supplements are often not “pure omega-3,” the omega-3 benefit may be “negated by the intake of other fats in the supplements.”

A diet with high omega-3 intake is “still felt to be healthful though difficult to prove,” Dr. Fialkow said. Meanwhile, prescription medications that are pure omega-3 “can positively impact lipid profiles though, also, there is no proof that they positively impact cardiovascular disease,” he added.

At least two large, randomized controlled trials focusing on the use of prescription omega-3 and cardiovascular disease are ongoing. When completed, these studies should determine, once and for all, if there is truth to the benefit, he said.

Average Age of Study Participants: 64
There were 77,917 people in the trials that were examined in the most recent study published last week — 61 percent men. The average age was 64. Studies lasted, on average, 4.4 years, and the dose of omega-3s ranged from 226 to 1,800 milligrams a day. The study’s authors said that fish oil supplements lowered the risk of death by 7 percent in these trial participants, and the risk of nonfatal heart attack by 3 percent. Those percentages are not high enough to be considered significant, according to the study.

While the American Heart Association recommends supplements for people with coronary artery disease who may not get enough omega-3s from foods in their regular diets, the study’s researchers found “no support” for those guidelines.

“The results of this analysis of large studies provide no support for current recommendations to use fish oil supplements to prevent heart attacks and strokes,” said lead researcher Robert Clarke, M.D., a professor of epidemiology and population medicine at the University of Oxford in the United Kingdom, and a lead researcher in the study.

Supplements No Substitute for Prescribed MedsIn a 2016 article published in the American Journal of Cardiovascular Drugs, authored by Dr. Fialkow, he cautions against the use of dietary supplements as a substitute for prescribed medication. Dietary supplement fish oils containing omega-3s are heavily promoted for heart health or for their anti-inflammatory qualities that can help people manage arthritis and joint pain. But there is no clinical data supporting these claims.

Most dietary omega-3 supplements, and most prescription omega-3 formulations, contain EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). Products containing both EPA and DHA can have different impacts on low-density lipoprotein cholesterol (LDL-C) — most commonly known as the “bad cholesterol.”

“Omega-3 fatty acids are essential parts of our diet. However, Dietary supplement fish oils containing omega-3s contain lower levels of EPA and DHA than prescription products and are not approved or intended to treat disease,” says Fialkow, who is also a certified lipidologist, specializing in the control of high cholesterol and other lipid disorders including metabolic syndrome and hypertriglyceridemia, which is often seen in pre-diabetes and diabetes. He adds that cold-water fish and seafood tend to have high levels of omega-3 fats.

Over the last decade, several prescription omega-3 fatty acid products have been approved by the U.S. Food and Drug Administration for the treatment of hypertriglyceridemia, a condition in which triglyceride levels are elevated, based on data from clinical intervention trials. But fish oil supplements containing omega-3s are not regulated by the FDA.